Add shortcut to install an app to Private space

Introduce long-press shortcut to install a copy
of the main user app to private space.

Test: manual, installed apps in different stores
and tried shortcut
https://screenshot.googleplex.com/6oAVamTytiYmvPC.png
Bug: 316118005
Flag: ACONFIG com.android.launcher3.Flags.enable_private_space_install_shortcut DEVELOPMENT

Change-Id: I702cd2a27388e3cc6e9e126308d5479836ba6655

src/com/android/launcher3/allapps/ActivityAllAppsContainerView.java

@@ -1315,6 +1315,10 @@ public class ActivityAllAppsContainerView<T extends Context & ActivityContext>
                 : mViewPager == null ? AdapterHolder.MAIN : mViewPager.getNextPage();
     }
 
+    public PrivateProfileManager getPrivateProfileManager() {
+        return mPrivateProfileManager;
+    }
+
     /**
      * Adds an update listener to animator that adds springs to the animation.
      */